Post on 30-Jan-2021
CS120A and CS125Visibility and Present
Weather Sensors
Issued: 17/12/2020 Copyright © 2018-2020 Campbell Scientific CSL I.D - 1141
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prepaid. The guarantee will not apply to:
Equipment which has been modified or altered in any way without thewritten permission of Campbell Scientific
Batteries
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obligation thereunder is in lieu of all other guarantees, expressed or implied,
including those of suitability and fitness for a particular purpose. Campbell
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Please inform us before returning equipment and obtain a Repair Reference
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Campbell Scientific Ltd,
80 Hathern Road,
Shepshed, Loughborough, LE12 9GX, UK
Tel: +44 (0) 1509 601141
Fax: +44 (0) 1509 270924 Email: support@campbellsci.co.uk
www.campbellsci.co.uk
About this manual
Some useful conversion factors:
Area: 1 in2 (square inch) = 645 mm2
Length: 1 in. (inch) = 25.4 mm 1 ft (foot) = 304.8 mm
1 yard = 0.914 m 1 mile = 1.609 km
Mass: 1 oz. (ounce) = 28.35 g 1 lb (pound weight) = 0.454 kg
Pressure: 1 psi (lb/in2) = 68.95 mb
Volume: 1 UK pint = 568.3 ml 1 UK gallon = 4.546 litres 1 US gallon = 3.785 litres
Recycling information
At the end of this product’s life it should not be put in commercial or domestic refuse but sent for recycling. Any batteries contained within the product or used during the products life should be removed from the product and also be sent to an appropriate recycling facility.
Campbell Scientific Ltd can advise on the recycling of the equipment and in some cases arrange collection and the correct disposal of it, although charges may apply for some items or territories.
For further advice or support, please contact Campbell Scientific Ltd, or your local agent.
Campbell Scientific Ltd, Campbell Park, 80 Hathern Road, Shepshed, Loughborough, LE12 9GX, UK Tel: +44 (0) 1509 601141 Fax: +44 (0) 1509 270924
Email: support@campbellsci.co.uk www.campbellsci.co.uk
Safety DANGER — MANY HAZARDS ARE ASSOCIATED WITH INSTALLING, USING, MAINTAINING, AND WORKING ON OR AROUND TRIPODS, TOWERS, AND ANY ATTACHMENTS TO TRIPODS AND TOWERS SUCH AS SENSORS, CROSSARMS, ENCLOSURES, ANTENNAS, ETC. FAILURE TO PROPERLY AND COMPLETELY ASSEMBLE, INSTALL, OPERATE, USE, AND MAINTAIN TRIPODS, TOWERS, AND ATTACHMENTS, AND FAILURE TO HEED WARNINGS, INCREASES THE RISK OF DEATH, ACCIDENT, SERIOUS INJURY, PROPERTY DAMAGE, AND PRODUCT FAILURE. TAKE ALL REASONABLE PRECAUTIONS TO AVOID THESE HAZARDS. CHECK WITH YOUR ORGANIZATION'S SAFETY COORDINATOR (OR POLICY) FOR PROCEDURES AND REQUIRED PROTECTIVE EQUIPMENT PRIOR TO PERFORMING ANY WORK.
Use tripods, towers, and attachments to tripods and towers only for purposes for which they are designed. Do not exceed design limits. Be familiar and comply with all instructions provided in product manuals. Manuals are available at www.campbellsci.eu or by telephoning +44(0) 1509 828 888 (UK). You are responsible for conformance with governing codes and regulations, including safety regulations, and the integrity and location of structures or land to which towers, tripods, and any attachments are attached. Installation sites should be evaluated and approved by a qualified engineer. If questions or concerns arise regarding installation, use, or maintenance of tripods, towers, attachments, or electrical connections, consult with a licensed and qualified engineer or electrician.
General • Prior to performing site or installation work, obtain required approvals and permits. Comply with all
governing structure-height regulations, such as those of the FAA in the USA.• Use only qualified personnel for installation, use, and maintenance of tripods and towers, and any
attachments to tripods and towers. The use of licensed and qualified contractors is highly recommended.• Read all applicable instructions carefully and understand procedures thoroughly before beginning work.• Wear a hardhat and eye protection, and take other appropriate safety precautions while working on or
around tripods and towers.• Do not climb tripods or towers at any time, and prohibit climbing by other persons. Take reasonable
precautions to secure tripod and tower sites from trespassers.• Use only manufacturer recommended parts, materials, and tools.
Utility and Electrical • You can be killed or sustain serious bodily injury if the tripod, tower, or attachments you are installing,
constructing, using, or maintaining, or a tool, stake, or anchor, come in contact with overhead orunderground utility lines.
• Maintain a distance of at least one-and-one-half times structure height, or 20 feet, or the distancerequired by applicable law, whichever is greater, between overhead utility lines and the structure (tripod,tower, attachments, or tools).
• Prior to performing site or installation work, inform all utility companies and have all underground utilitiesmarked.
• Comply with all electrical codes. Electrical equipment and related grounding devices should be installedby a licensed and qualified electrician.
Elevated Work and Weather • Exercise extreme caution when performing elevated work.• Use appropriate equipment and safety practices.• During installation and maintenance, keep tower and tripod sites clear of un-trained or non-essential
personnel. Take precautions to prevent elevated tools and objects from dropping.• Do not perform any work in inclement weather, including wind, rain, snow, lightning, etc.
Maintenance • Periodically (at least yearly) check for wear and damage, including corrosion, stress cracks, frayed cables,
loose cable clamps, cable tightness, etc. and take necessary corrective actions.• Periodically (at least yearly) check electrical ground connections.
WHILE EVERY ATTEMPT IS MADE TO EMBODY THE HIGHEST DEGREE OF SAFETY IN ALL CAMPBELL SCIENTIFIC PRODUCTS, THE CUSTOMER ASSUMES ALL RISK FROM ANY INJURY RESULTING FROM IMPROPER INSTALLATION, USE, OR MAINTENANCE OF TRIPODS, TOWERS, OR ATTACHMENTS TO TRIPODS AND TOWERS SUCH AS SENSORS, CROSSARMS, ENCLOSURES, ANTENNAS, ETC.
Contents
PDF viewers note: These page numbers refer to the printed version of this document. Use
the Adobe Acrobat® bookmarks tab for links to specific sections.
1. Introduction ................................................................. 1
1.1 General Safety........................................................................................... 2
1.2 Sensor Unit Safety .................................................................................... 2
1.3 Principle of operation ................................................................................ 3
1.4 Recommended Tools ................................................................................ 6
1.5 Quickstart .................................................................................................. 6
2. Measurement specification ........................................ 6
3. Technical specification .............................................. 7
3.1 Electrical specification .............................................................................. 7
3.2 Optical specification ................................................................................. 7
4. Communications specification .................................. 8
4.1 Communications electrical specifications ................................................. 8
4.2 Supported data rates and formats .............................................................. 8
5. Environmental specifications .................................... 9
6. Mechanical specifications .......................................... 9
6.1 Dimensions ............................................................................................... 9
6.2 Weights ................................................................................................... 10
6.3 Mounting................................................................................................. 10
7. Installation procedure .............................................. 10
7.1 Equipment grounding ............................................................................. 11
7.2 Mounting the sensor ................................................................................ 12
7.3 Optional Campbell Scientific Mount ...................................................... 14
8. Sensor internal connectors’ description ................ 17
8.1 Sensor recommended wiring using Campbell Scientific cables ............. 19
9. HygroVUE 5, HygroVUE 10 or CS215 T/RH Sensor (CS125 only) ................................................................... 21
10. Functions of the internal switches ........................ 23
ii
11. Message Formats: A breakdown of the different default outputs of the sensor –
Basic/Partial/Full ............................................... 24
11.1 Visibility only messages ....................................................................... 25
11.2 Messages with SYNOP Present Weather Codes (CS125 only) .............. 26
11.3 Messages with METAR Present Weather Codes (CS125 only) ............. 27
11.4 Messages with Generic SYNOP Present Weather Codes (CS125 only) 28
11.5 Example sensor message outputs .......................................................... 33
11.6 Custom message format ........................................................................ 34
12. Interface methods – Device Configuration
Utility/Command line/Menu .................................. 36
12.1 Configuring a PC for talking to the sensor ........................................... 37
13. Definition of the variables that can be set by the user on the sensor ........................................ 37
14. Command line mode............................................... 39
14.1 The SET Command .............................................................................. 40
14.1.1 Example of a SET Command ................................................... 40
14.2 The SETNC Command ......................................................................... 41
14.2.1 Example of a SETNC Command .............................................. 41
14.3 The MSGSET Command ...................................................................... 41
14.4 The GET Command .............................................................................. 43
14.5 The MSGGET Command ..................................................................... 45
14.6 The POLL Command – Polling the sensor ........................................... 46
14.7 The ACCRES Command – Resetting the accumulation value ............. 47
15. Entering the sensor menu system ........................ 47
16. Calibrating the sensor ............................................ 53
16.1 Visibility calibration ............................................................................. 53
16.2 Dirty window zero calibration .............................................................. 57
16.3 Internal temperature check (CS125) ..................................................... 57
17. Performing an operating system update .............. 58
18. Cleaning .................................................................. 60
19. Lubricating the enclosure screws ......................... 61
20. Desiccant ................................................................. 61
Addendum .................................................................Add-1
iii
Appendices
A. Sensor Block Diagram ........................................... A-1
B. Example C code of the checksum CRC-16 ........... B-1
C. Present Weather Codes ........................................ C-1
D. A comparison of the two alternative visibility calibrations ........................................................... D-1
Figures
1-1 Particles in the sample volume scatter light in all directions, including
into the detector ....................................................................................... 3
1-2 Signals from large, slow falling snowflakes and smaller, faster,
raindrops .................................................................................................. 4
1-3 Defining possible precipitation types based on wet bulb and dry
bulb temperatures ..................................................................................... 5
1-4 A typical size/speed map used by the CS125 present weather
algorithm ................................................................................................... 5
7-1 Airflow ................................................................................................... 11
7-2 Grounding boss ....................................................................................... 12
7-3 Mounting arrangement ........................................................................... 13
7-4 Mounting to a flat surface ....................................................................... 13
7-5 Use of band clamps ................................................................................ 14
7-6 Optical sensor mast ................................................................................. 15
7-7 Mounting footprint ................................................................................. 16
8-1 Connections ............................................................................................ 17
8-2 Communications and power connections ............................................... 19
8-3 Communications and power connector .................................................. 20
8-4 Configuration cable ................................................................................ 20
8-5 USB configuration cable ........................................................................ 20
9-1 Connection for the optional HygroVUE 5, HygroVUE 10 &
CS215 T/RH sensors .......................................................................... 22
10-1 Internal switches ................................................................................... 23
16-1 Calibration disk .................................................................................... 55
16-2 Mounting calibration disk ..................................................................... 56
17-1 Sensor DevConfig download instructions ............................................ 58
17-2 Sensor DevConfig screen when OS update is complete ....................... 59
Tables
10-1 Internal switch functions ..................................................................... 24
11-1 Summary of message IDs and descriptions ......................................... 30
11-2 Summary of system alarms and descriptions ....................................... 31
13-1 User definable settings and descriptions .............................................. 37
iv
1
CS120A and CS125 Visibility and Present Weather Sensors
1. Introduction The CS120A is a visibility sensor. The CS125 additionally detects and reports
present weather in the form of SYNOP, METAR or NWS codes. The CS125 has
the same specification for visibility measurement as the CS120A. It is possible to
upgrade a CS120A to a CS125, please contact Campbell Scientific for more
details.
The sensors are infra-red forward scatter visibility and present weather sensors for
automatic weather stations including road, marine and airport based stations.
They both use the well-established forward scatter system for visibility
measurement, utilising a 42º scatter angle. The CS125 uses high speed sampling
to reduce missed events and improves response to other suddenly changing
conditions.
The CS125 has a temperature sensor mounted in the cross arm used as part of the
process for identifying precipitation.
When an optional CS215 or HygroVUE temperature and RH sensor is connected,
the CS125 can distinguish wet and dry obscuration (for example mist and haze)
and make more precise discrimination between liquid and frozen precipitation.
Dew heaters are provided to keep the sensor optics clear of condensation and more
powerful hood heaters to prevent the build up of snow or ice.
This sensor is certified for Aviation use by the German Meteorological Service,
Deutscher Wetterdienst (DWD) (see Section 1.3 regarding the settings).
CS120A and CS125 Visibility and Present Weather Sensors
2
1.1 General Safety
This manual provides important safety considerations for the installation,
operation and maintenance of the sensor. These safety considerations are
classified into three levels:
Warnings alert the installer or user to serious hazards. Ignoring these warnings could result in injury or death and/or irrevocable damage to the sensor unit.
Cautions warn of potential hazards. Ignoring these cautions could result in the sensor being damaged and data being lost.
Notes highlight useful information in the installation, use and
maintenance of this product. These should be followed carefully in
order to gain the maximum benefit from the use of this product.
1.2 Sensor Unit Safety
The sensor has been checked for safety before leaving the factory and
contains no internally replaceable or modifiable parts.
Do not modify the sensor unit. Such modifications will lead to damage of the unit and could expose users to dangerous light levels and voltages.
In unusual failure modes and environmental conditions the sensor hood could become hot. In normal operation they will be at ambient temperature or slightly above.
Ensure that the correct voltage supply is provided to the sensor.
WARNING
CAUTION
NOTE
WARNING
WARNING
CAUTION
Instruction Manual
3
1.3 Principle of operation
Figure 1-1. Particles in the sample volume scatter light in all directions, including into the detector
The CS120A and CS125 comprise an emitter and detector aligned as in
Figure 1-1. The emitter produces a beam of near infra-red light pulsed at 1 kHz. A
detector has a field of view which overlaps the beam and is inclined at 42 degrees
to it. Light scattered by a particle (for example a fog droplet or particle of
precipitation) from the overlap or sample volume towards the detector is detected
by a photodiode and recorded as a signal. The size of the signal is therefore
proportional to the extinction of the emitted beam caused by scattering. The
scattering signal averaged over one second is used to calculate an extinction
coefficient or EXCO assuming the relationship between forward scatter and
EXCO is linear. Sixty one second averages are then themselves averaged to give a
one minute average EXCO. This is then converted to a value of Meteorological
Optical Range (MOR) using Koschmieder’s law:
MOR = 3/EXCO where MOR is in km and EXCO in units of km-1.
The CS125 calibration for visibility was derived by comparison with other high
grade, forward scatter sensors and has also been verified in a study by trained
meteorological observers. This is called the MOR calibration in this manual.
An alternative calibration, known as TMOR, is also available. This was derived
by following the ICAO procedure of calibrating the sensor against a
transmissometer. An empirical equation to convert from MOR to TMOR was
developed.
CS120A and CS125 Visibility and Present Weather Sensors
4
This non-linear equation results in significantly higher visibility readings at lower
visibilities below 5000 metres. Further details of the calibration and graphs
comparing the two calibration options are given in Appendix D.
The TMOR calibration should be used for aviation applications as it is considered
to give more representative visibility values for a plane landing and viewing
landing lights. Use of the TMOR calibration is obligatory for use of this sensor on
German airfields.
The CS125 can be switched between outputting data using the original MOR or
the alternative TMOR calibration by using a configuration switch (See Section
10). Sensors made from early December 2020 leave the factory with this switch
set to ON to make the sensor output values according to the TMOR calibration.
The CS125 is capable of identifying weather type in addition to measuring
visibility. It does this by analysing the amplitude and width of spikes in the APD
signal corresponding to particles of precipitation passing through the sample
volume. The amplitude of the signal is a guide to the size of the particle and the
width, because it represents the time taken for the particle to fall through the
sample volume, is proportional to the fall speed, see Figure 1-2.
Figure 1-2. Signals from large, slow falling snowflakes and smaller, faster, raindrops
The CS125 also has a temperature sensor. These three parameters, fall speed, size
and temperature are used to identify the type of particle. If an additional external
temperature and relative humidity probe is connected then a wet-bulb temperature
can be calculated. This provides useful additional information identifying particles
more accurately especially, between liquid and frozen around 0°C.
Figure 1-3 shows how these temperatures are used to define possible precipitation
types around 0°C.
Instruction Manual
5
Figure 1-3. Defining possible precipitation types based on wet bulb and dry bulb temperatures
The processing algorithm then works with several ‘maps’ such as Figure 1-4 to
identify each particle.
Figure 1-4. A typical size/speed map used by the CS125 present weather algorithm
CS120A and CS125 Visibility and Present Weather Sensors
6
1.4 Recommended Tools
The following installation tools are recommended:
10 mm open spanner/wrench (for grounding boss, must be open ended)
13 mm spanner/wrench
19 mm open spanner/wrench (for cable glands, must be open ended)
2 mm flat screwdriver
Number 2 cross head screwdriver
1.5 Quickstart
The sensor is shipped set to the following default communication RS-232, 8N1,
38400 baud, a sensor ID = 0 and set to transmit default messages, full format,
visibility only for the CS120A, SYNOP present weather full format for the
CS125, at 1 minute intervals (see Section 11).
To start using the CS120A or CS125, first connect a DC supply matching the
specification in Section 3.1 to the red and black wires on the ‘D-connector’ (see
Figure 8-3) and connect to a PC communications port with a terminal emulator set
to RS-232, 38400 baud, 8N1. After a couple of minutes, data messages will be
received. Typing ‘open 0’ will access the menu structure, see Section 15.
2. Measurement specification Minimum
Value
Nominal
Value
Maximum
Value
Visibility characteristics
Reported visibility (metric) 5 metres - 75,000
metres
Reported visibility (imperial) 16 feet - 46 miles
Visibility accuracy calibration
against factory calibration disk**
- +/- 2% -
Visibility accuracy up to 600 m - +/-8% -
Visibility accuracy up to 10,000 m - +/-10% -
Visibility accuracy up to 15,000 m - +/-15% -
Visibility accuracy above 15,000 m - +/-20% -
Precipitation characteristics, water equivalent (CS125 only)
Reported accumulation range 0 – 999.9 mm
Accumulation accuracy +/-15%
Accumulation resolution 0.1 mm
Reported intensity range (up to *) 0 - 999.99 mm/hr
Intensity accuracy** +/-15%
Intensity resolution 0.01 mm/hr
*The maximum intensity reported is dependent on the mixture of precipitation falling.
**Please refer to Section 1.3 regarding the calibration options for the sensor.
Instruction Manual
7
3. Technical specification
3.1 Electrical specification
Minimum
Value
Nominal
Value
Maximum
Value
Main power supply for DSP and dew heaters
Power supply, (DC only) 7V 12V 30V(1)
Current consumption sampling
continuously with dew heaters ON and
RS-232 communications active(2, 3)
(at 12V DC)
- 200 mA 248 mA
Current consumption sampling
continuously with dew heaters disabled
(at 12V DC)
- 110 mA 151 mA
Current consumption without any
sampling occurring and dew heaters
disabled (at 12V DC)
- 21 mA 30 mA
Hood heater power supply
Hood heater voltage (AC or DC) - 24V(3) 30V(4)
Hood heater wattage (at 24V AC or
DC)
- 60W(5) -
User alarm outputs
User output high level (at 85ºC) 3.8V - -
User output high level (at 25ºC ) 4.13V - -
User output low (All temperatures) 0.25V - 0.55V
User output current - - 32 mA
(1) If a CS215 or HygroVUE probe is being used with a CS125 the supply voltage should not exceed 28V.
(2) The RS-232 communications interface will automatically turn itself off when not transmitting.
(3) If hood heaters are not being used ensure ‘Hood heater override’ (details in Section 13) is set to
off.
(4) It is recommended that the hood heaters are run at 24V AC/DC. It is possible to run the heaters at any voltage below 24V but the heaters will generate proportionally less heat reducing their ability
to prevent ice build-up.
(5) Each hood takes 30W, 60W is the total for both hoods on the sensor together.
If a CS215 or HygroVUE probe is being used the supply voltage should not exceed 28V.
3.2 Optical specification
Minimum
Value
Nominal
Value
Maximum
Value
Optical characteristics
LED centre wavelength - 850 nm -
LED spectral bandwidth - +/-35 nm -
Pulse characteristics
CAUTION
CS120A and CS125 Visibility and Present Weather Sensors
8
Light pulse rate - 1KHz -
4. Communications specification
4.1 Communications electrical specifications
Minimum
Value
Nominal
Value
Maximum
Value
RS-232 Communications(1)
RS-232 input threshold Low 0.8V 1.5V -
RS-232 input threshold High - 2.0V 2.4V
RS-232 input absolute maximum -15V - +15V
RS-232 input resistance 12K - -
RS-232 output voltage low - - 0.4V
RS-232 output voltage high (into
3K)
4.4V - -
RS-485 Communications
RS-485 input threshold voltage -0.2V - +0.2V
RS-485 output (Unloaded) - - 5V
RS-485 output (Load 50) 2V - -
Maximum voltage at any terminal(2) -7V - +7V
(1) The RS-232 communications interface will automatically turn itself off when not transmitting.
(2) The ground of the sensor and the ground of any RS-485 equipment cannot be further apart than this voltage. The sensor ground (pin 1) on connector B, see page 18, can be connected to the
ground of the host equipment. This will reduce any parasitic currents.
4.2 Supported data rates and formats
Serial setting 8N1
Supported data rates
• 1200 bps
• 2400 bps
• 9600 bps
• 19200 bps
• 38400 bps - default
• 57600 bps
• 115200 bps
Supported formats
• RS-232 (Full duplex only), default
• RS-485 (Half duplex)
• 8 bit data bytes
• 1 stop bit
• Parity checking is not supported as most communication protocols used by
the CS125 have built in checksums as well as checks that communications
have been understood.
Instruction Manual
9
5. Environmental specifications
Minimum
Value
Nominal
Value
Maximum
Value
Sensor temperature ranges
Operating temperature -25°C - +60°C
Extended operating temperature -40°C - +70°C (1)
Storage temperature -40°C - +85°C
Sensor humidity ranges
Operating humidity range 0% - 100%
Sensor heater thresholds
Dew heater Turn On - 40°C -
Hood heater Turn On - 25°C -
(1) Extended temperature ranges are only guaranteed if the sensor has been tested by Campbell Scientific and verified within this temperature range. Some degradation of absolute accuracy can
be expected at the extremes of the extended ranges.
6. Mechanical specifications
6.1 Dimensions
CS120A and CS125 Visibility and Present Weather Sensors
10
6.2 Weights
Sensor weight: 3 Kg
Shipping weight: 6 Kg (including packing box)
6.3 Mounting
Sensor mounting: Bracket mounts on a vertical pole 32-52.5 mm diameter. The
mounting bracket has cut-outs for band clamps for larger
diameter masts.
7. Installation procedure The sensor measures environmental variables and is designed to be located in
harsh weather conditions. However, there are a few considerations to take into
account if accurate and representative data from a site are to be obtained.
The descriptions in this section are not exhaustive. Please refer to
meteorological publications for further information on locating
weather instruments
The sensor should be sited in a position representative of local weather conditions
and not of a specific microclimate (unless the analysis of microclimate weather is
being sought).
The sensor has good resistance to background light but it is a good idea to avoid
locations where the transmitter is pointing at a light scattering or reflecting
surface. Ideally, the receiver should point north in the northern hemisphere or
south in the southern hemisphere but this is not critical. This is because it is more
important to make sure the receiver is not pointing towards any possible sources
or reflected light in its field of view, for instance nearby sensors or enclosures
mounted below it on a mast. Where those objects cannot be moved, pointing the
sensor away from North/South is acceptable. Failure to do this can result in the
sensor reporting a DC light saturation error when there is bright sunlight.
To give non-microclimatic measurements the sensor should be sited away from
possible physical obstructions that could affect the fall of precipitation. The sensor
should also be positioned away from sources of heat, electrical interference and in
such a position as to not have direct light on the sensor lenses. Whenever possible,
the sensor should be located away from windbreaks.
Several zones have been identified upwind and downwind of a windbreak in
which the airflow is unrepresentative of the general speed and direction. Eddies
are generated in the lee of the windbreak and air is displaced upwind of it. The
height and depth of these affected zones varies with the height and to some extent
the density of the obstacle.
Generally, a structure disturbs the airflow in an upwind direction for a distance of
about twice the height of the structure, and in a downwind direction for a distance
of about six times the height. The airflow is also affected to a vertical distance of
about twice the height of the structure. Ideally, therefore, the sensor should be
located outside this zone of influence in order to obtain representative values for
the region.
NOTE
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11
Figure 7-1. Airflow
In order to reduce the service frequency with the unit, the sensor should be placed
away from sources of contamination, in the case of roadside monitoring; larger
mounting poles can be used. More regular maintenance will be required when the
instrument is placed in areas where contamination is unavoidable or where
measurements may be safety critical.
The WMO recommend a sample volume height of 1.5 m. However, for
applications such as aviation or road visibility other heights may be appropriate.
If operating a sensor indoors it is likely that there will be sources of
light and/or reflections that will create false readings and erratic
results.
If carrying out simple checks, blocking a lens or the sample volume
will simulate an INCREASE in visibility not a decrease.
7.1 Equipment grounding
The sensor must be properly grounded. It is sufficient to ground the mounting
bracket and if the sensor is connected to a grounded metal mast, and in electrical
contact with it, then this will be sufficient. Otherwise, the mounting bracket
should be earthed and a grounding boss is supplied to allow this.
A ground wire with a minimum cross section of 6 mm2 and maximum length of
5 m should be used.
The pole and foundations of a pole mounted installation will provide some basic
lightning protection and protection against radio frequency interference and
should also be correctly grounded.
NOTE
NOTE
CS120A and CS125 Visibility and Present Weather Sensors
12
Figure 7-2. Grounding boss
7.2 Mounting the sensor
A quick release pole mounting kit is supplied with the sensor.
If a power supply enclosure has been supplied with the sensor it can be mounted
on the pole, near its base using the brackets supplied with the enclosure.
Alternatively the power supply can be mounted elsewhere, e.g. on a wall at some
distance from the sensor. The power supply enclosure should be mounted away
from the sensor head to avoid wind flow disturbance or rain drops bouncing back
up into the sensor’s sensing volume.
Take care not to overtighten the nuts on the bolts, as it may be possible to distort and/or damage the brackets or DSP plate by doing so, and/or the nuts may seize up. Only tighten the nuts to a degree necessary to hold the sensor firmly in place.
Where the sensor is to be mounted onto another type of mast, please refer to the
manual for that mast for mounting details.
Ensure that the sensor is mounted according to the following figure. Do not reposition, once fixings are tightened, by forcing the arms of the unit as this can cause damage.
CAUTION
CAUTION
Instruction Manual
13
Do not remove the mounting plate as this will compromise resistance to water ingress.
Figure 7-3. Mounting arrangement
If you need to mount the sensor to a flat surface, remove the plastic formers from
the mounting brackets and use the holes as shown in Figure 7-4.
If mounting to a flat surface ensure that there is no obstruction to
airflow through the sample volume.
Figure 7-4. Mounting to a flat surface
CAUTION
NOTE
CS120A and CS125 Visibility and Present Weather Sensors
14
Slots are provided to allow band clamps to be used with larger diameter masts, see
Figure 7-5.
Figure 7-5. Use of band clamps
7.3 Optional Campbell Scientific Mount
A Campbell Scientific ‘optical sensor mount’ is available. This will put the
sample volume at about 1.5 m in compliance with the WMO ‘Guide to
Meteorological Instruments and Methods of Observation’, 7th Edition, Section
9.3.4.
Instruction Manual
15
Figure 7-6. Optical sensor mast
If one is to be used, use the following installation instructions.
Install the mount on a concrete foundation. If one does not already exist then a
concrete foundation should be constructed at least 600 mm square and 600 mm
deep. Ensure the ground consistency is not too loose and will be able to support
the mount and concrete foundation.
CS120A and CS125 Visibility and Present Weather Sensors
16
Drill four 12 mm diameter holes using the mount base as a template or using the
following in Figure 7-7 to a depth of 77 mm.
Figure 7-7. Mounting footprint
Clean the holes of all debris.
Place washers and nuts on the ends of the wedge anchors supplied (to protect the
threads during installation).
Hammer the wedge anchors into the holes until the start of the threads are below
the surface.
Tighten the nuts until about 25 mm of thread protrudes above the surface.
Remove the washers and nuts from the protruding length screw. Then lower the
mount into place.
Finally secure the mount with the washers and nuts.
If the surface is not level and flat it may be necessary to add washers under the
base on one or more of the foundation screws.
Instruction Manual
17
8. Sensor internal connectors’ description The sensor has four standard IP66 rated glands. The first gland is by default used
by the power/communications line. This comprises the 7-30 V for the main
electronics, and the serial communications wires. The sensor is supplied with 5 m
cable already connected.
The second gland is used for the 24 V feeds for the hood heaters fitted with a 5 m
cable.
Glands 3 and 4 are spare. If user alarms are connected they usually use gland 3
and if a CS215 or HygroVUE probe is fitted this usually uses gland 4.
If you need to run cables through the cable glands follow these guidelines. If a
torque wrench is available use a torque of 2.5 Nm (do not over tighten).
Otherwise tighten with fingers as tight as possible and then add a further ¾ turn
with a 19 mm spanner (do not over tighten).
The glands are suitable for cables between 5 and 9 mm diameter.
If the power cable is incorrectly wired to the sensor then damage can be done to the unit.
10 m is the longest length of the cable type supplied recommended. In particular, additional RS-485 communication should be twisted pair. Please contact Campbell Scientific if you wish to use a longer length of cable.
Figure 8-1. Connections
CAUTION
CAUTION
CS120A and CS125 Visibility and Present Weather Sensors
18
Connector A - Five way connector
Pin number Description Notes
Pin 1 +ve supply Main electronics +ve supply input
Pin 2 0V Auxiliary Electronics 0V. Common with the main electronics 0V.
Pin 3 Hood low This is for the hood heater power supply. If the hood heater supply is
DC it should be the negative connection and if it is AC it should be
the ‘neutral’ or ‘ground’ connection if there is one.
Pin 4 0V Auxiliary Electronics 0V. Common with the main electronics 0V.
Pin 5 Hood high This is for the hood heater power supply. If the hood heater supply is
DC it should be the positive connection.
To avoid damage to noise filters on the hood heater inputs if the heater voltage is DC the –ve connection should be made to pin 3 and the +ve to pin 5. If the heater voltage is AC with a ground or neutral wire then this should be connected to pin 3. Pin 3 should not be more than 5 volts from the main electronics 0V.
Connector B - Three way connector
Pin number Description Notes
Pin 1 0V 0V connection for serial communications. This connection is
common with the main electronics 0V (Connector A, pin 2).
Pin 2 Receive RS-232 receive line, RXD, B/D+ for RS-485 half duplex
Pin 3 Transmit RS-232 transmit line, TXD, A/D− for RS-485 half duplex
It may be necessary to use a 120 ohm termination resistor to reduce signal
distortion when using RS-485 for cable runs over about 500 m and baud rates
above 38400. It should be connected between pins 2 and 3.
Connector C - Four way connector
Pin number Description Notes
Pin 1 0V 0V connection for user alarms. This connection is common with the
main electronics 0V (Connector A, Pin 2).
Pin 2 User 2 Output for user alarm 2
Pin 3 0V 0V connection for user alarms. This connection is common with the
main electronics 0V (Connector A, Pin 2).
Pin 4 User 1 Output for user alarm 1
CS125 only
Pin number Description
Pin 1 +12V
Pin 2 SDI-12
Pin 3 0V
To use these connections it is necessary to either use the cable gland
taking the hood heater power or, if the hood heater is also required,
to use different cables to those supplied. Please contact Campbell
Scientific if you need any advice on choice of cable.
CAUTION
NOTE
Instruction Manual
19
8.1 Sensor recommended wiring using Campbell Scientific cables (this cable is supplied already connected as standard)
The sensor is provided pre-wired with a default 5 m power and communications
cable which is terminated at one end with a 9 pin D-connector (DB9). The
D-connector can be connected directly to a PC or to a datalogger such as the
Campbell Scientific CR1000 using a suitable interconnecting cable such as the
SC110. If another type of connection is required then the D-connector should be
removed.
Figure 8-2. Communications and power connections
CS120A and CS125 Visibility and Present Weather Sensors
20
Figure 8-3. Communications and power connector
Two types of configuration cable are available from Campbell Scientific that plug
directly into connector B in place of the normal connector and cable. One has a
RS-232 or RS-485 output according to how the CS120A/CS125 is configured
(Figure 8-4) and one has a USB output (Figure 8-5).
If the lid is removed, take care not to overtighten the fixing screws.
A small gap should remain between the lid and box.
Figure 8-4. Configuration cable
Figure 8-5. USB configuration cable
NOTE
Instruction Manual
21
9. HygroVUE 5, HygroVUE 10 or CS215 T/RH Sensor (CS125 only)
The CS125 has a temperature sensor mounted in the crossarm that is used in
determining precipitation type.
A HygroVUE 5, HygroVUE 10 or CS215 temperature and RH sensor can be
connected to a CS125. This is recommended as it will improve the performance of
the CS125 in identifying precipitation and allows it to, for example, distinguish
between mist and haze. Precipitation identification at temperatures close to
freezing will be much improved by a CS215 and its use is highly recommended in
regions where temperatures close to 0°C are common if information on
precipitation type is important. It also allows RH information to be included in
data messages.
If a HygroVUE 5, HygroVUE 10 or CS215 is connected then the temperature
used for assessment of precipitation type and included in data messages will come
from the HygroVUE 5, HygroVUE 10 or CS215 instead of the temperature sensor
mounted in the cross arm.
The connections for the HygroVUE 5, HygroVUE 10 or CS215 are shown in
Figure 9-1. The HygroVUE 5 can be mounted in the Rad 6, the HygroVUE 10 in
the Rad 10E, or CS215 itself can be mounted in a Met20 screen on the same mast
as the CS125. The screen can be mounted on the top section of an OSM1 optical
mast below a CS125.
WMO – No. 8, 2.1.4.1 recommends temperature measurement at a height of
between 1.2 and 2.0 m above ground. The screen should be below the height of
the CS125 electronics box.
CS120A and CS125 Visibility and Present Weather Sensors
22
Connections for temperature
and RH sensor
Figure 9-1. Connection for the optional HygroVUE 5, HygroVUE 10 and CS215 T/RH sensors
CS215 WIRING
COLOUR FUNCTION PIN
Red +12V 1
Green SDI-12 2
Black Power Ground 3
Clear Shield 3
White Power Ground 3 or NC
HYGROVUE 5 & HYGROVUE 10
WIRING
COLOUR FUNCTION PIN
Brown +12V 1
White SDI-12 2
Black Power Ground 3
Clear Shield 3
Instruction Manual
23
10. Functions of the internal switches The sensor is equipped with four switches located within the main enclosure.
These switches perform certain functions at power up, their functions are detailed
in Figure 10-1.
The switches are only read during the power up sequence of the
sensor. This means that if the switches are pressed whilst the sensor
is running nothing will happen, the sensor will need to be power
cycled leaving at least 10 seconds with the sensor off for any of
their functions to be performed.
Figure 10-1. Internal switches
IMPORTANT
CS120A and CS125 Visibility and Present Weather Sensors
24
Table 10-1. Internal switch functions
Switch number Function
4 When switched ON the sensor uses the TMOR
calibration and OFF it uses the MOR calibration.
Please refer to Section 1.3 for a description of
these two calibration options.
3 When switched to the ON position and the sensor
is power cycled this switch temporarily sets the
sensor communications port to a default RS-232
communication state at 38400 baud. This is useful
during field tests or maintenance when the sensor
has been remotely configured for RS-485 mode or
a baud rate your PC does not support. This change
is temporary and will not be stored to flash.
However, if the menu system is accessed and a
‘Save and exit’ command is performed these new
data rate settings will be committed to flash.
Once this switch is returned to its OFF position
and the sensor is power cycled the sensor will
return to its previous communications settings.
2 Reserved for future use, set to OFF.
1 When switched to the ON position this switch
will reset the sensor to its factory default values.
This reset will affect all communication settings.
This will take immediate effect upon power up.
NOTE: To use this the power supply must be
stable. Do not leave this switch set permanently.
If the lid is removed take care not to overtighten the screws when it
is replaced. A small gap should remain between the lid and box.
11. Message Formats: A breakdown of the different default outputs of the sensor – Basic/Partial/Full
The sensor has twelve different message formats available to the user. All
parameters are space delimited with a unique start and end character allowing easy
storage into any logger (see Section 15 on how to set default outputs). The
SYNOP Full Format message is the default message for the CS125 and the Full
Format Visibility only message is the default for the CS120A. These can be
selected from the Message – Sub 3 menu.
NOTE
CS125 MESSAGE - SUB 3
Set the message output format. Current format is: FULL SYNOP
- Basic = 0
- Partial = 1
- Full = 2
- Basic SYNOP = 3
- Partial SYNOP = 4
- Full SYNOP = 5
- Basic METAR = 6
- Partial METAR = 7
- Full METAR = 8
- Generic Basic SYNOP = 9
- Generic Partial SYNOP = 10
- Generic Full SYNOP = 11
- Custom output = 12
->
Instruction Manual
25
STX and ETX are hexadecimal command characters.
Refer to Appendix B for the checksum algorithm.
11.1 Visibility only messages
Basic Format, Visibility Only
ST
X
Mes
sag
e ID
Sen
sor
ID
Sy
stem
stat
us
Vis
ibil
ity
dis
tan
ce
Vis
ibil
ity
un
its
Ch
eck
sum
(CC
ITT
)
ET
X
Car
riag
e
retu
rn
Lin
e fe
ed
0x
02
0
M o
r F
XX
XX
0x
03
0x
0D
0x
0A
0 0 0 19837 M FC92 (Example message, visibility units = metres)
In the following example messages the shown message intervals are
12 seconds and visibility units are in metres unless otherwise
indicated.
Partial Format, Visibility Only
ST
X
Mes
sag
e ID
Sen
sor
ID
Sy
stem
sta
tus
Mes
sag
e
inte
rval
Vis
ibil
ity
dis
tan
ce
Vis
ibil
ity
un
its
Use
r al
arm
s
Ch
eck
sum
(CC
ITT
)
ET
X
Car
riag
e
retu
rn
Lin
e fe
ed
0x
02
1
M o
r F
0 0
XX
XX
0x
03
0x
0D
0x
0A
1 0 0 12 20405 M 0 0 EF07 (Example message)
NOTE
NOTE
NOTE
CS120A and CS125 Visibility and Present Weather Sensors
26
Full Format, Visibility Only (Default message for CS120A)
ST
X
Mes
sag
e
ID
Sen
sor
ID
Sy
stem
stat
us
Mes
sag
e
inte
rval
Vis
ibil
ity
dis
tan
ce
Vis
ibil
ity
un
its
Av
erag
ing
du
rati
on
Use
r
alar
ms
Sy
stem
alar
ms
10
ch
arac
ters
Ch
eck
sum
(CC
ITT
)
ET
X
Car
riag
e
retu
rn
Lin
e fe
ed
0x
02
2
M o
r F
0 0
0 0
0 0
0…
XX
XX
0x
03
0x
0D
0x
0A
2 0 0 12 68218 F 1 0 0 0 0 0 0 0 0 0 0 0 0 D378 (Example with Visibility Units = Feet)
2 0 0 12 21793 M 1 0 0 0 0 0 0 0 0 0 0 0 0 CB0F (Example with Visibility Units = Metres)
11.2 Messages with SYNOP Present Weather Codes (CS125 only)
SYNOP Present Weather Basic Format
ST
X
Mes
sag
e ID
Sen
sor
ID
Sy
stem
sta
tus
Vis
ibil
ity
dis
tan
ce
Vis
ibil
ity
un
its
SY
NO
P C
od
e
Ch
eck
sum
(CC
ITT
)
ET
X
Car
riag
e
retu
rn
Lin
e fe
ed
0x
02
3
M o
r F
0-9
9
XX
XX
0x
03
0x
0D
0x
0A
3 0 0 20428 M 0 20B8 (Example message)
SYNOP Present Weather Partial Format
ST
X
Mes
sag
e ID
Sen
sor
ID
Sy
stem
sta
tus
Mes
sag
e
inte
rval
Vis
ibil
ity
dis
tan
ce
Vis
ibil
ity
un
its
Use
r al
arm
s
Par
ticl
e co
un
t (m
inu
te)
Inte
nsi
ty (
mm
/h)
SY
NO
P C
od
e
Tem
per
atu
re (
deg
C)
Rel
ativ
e h
um
idit
y*
Ch
eck
sum
(CC
ITT
)
ET
X
Car
riag
e
retu
rn
Lin
e fe
ed
0x
02
4
M o
r F
0 0
0-9
9
XX
XX
0x
03
0x
0D
0x
0A
4 0 0 12 21157 M 0 0 0 0.00 0 24.1 -99 5A55 (Example message)
Instruction Manual
27
SYNOP Present Weather Full Format (Default message for CS125) S
TX
Mes
sag
e ID
Sen
sor
ID
Sy
stem
sta
tus
Mes
sag
e in
terv
al
Vis
ibil
ity
dis
tan
ce
Vis
ibil
ity
un
its
Av
erag
ing
du
rati
on
Use
r a
larm
s
Sy
stem
ala
rms
12
ch
arac
ters
Par
ticl
e co
un
t (m
inu
te)
Inte
nsi
ty (
mm
/h)
SY
NO
P C
od
e
Tem
per
atu
re (
deg
C)
Rel
ativ
e h
um
idit
y*
Ch
eck
sum
(CC
ITT
)
ET
X
Car
riag
e R
etu
rn
Lin
e fe
ed
0x
02
5
M o
r F
0 0
0 0
0 0
0…
0-9
9
XX
XX
0x
03
0x
0D
0x
0A
5 0 0 12 20880 M 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.00 0 24.1 -99 CAFA (Example message)
11.3 Messages with METAR Present Weather Codes (CS125 only)
METAR Present Weather Basic Format
ST
X
Mes
sag
e ID
Sen
sor
ID
Sy
stem
sta
tus
Vis
ibil
ity
dis
tan
ce
Vis
ibil
ity
un
its
ME
TA
R C
od
e
Ch
eck
sum
(CC
ITT
)
ET
X
Car
riag
e
retu
rn
Lin
e fe
ed
0x
02
6
M o
r F
XX
XX
0x
03
0x
0D
0x
0A
6 0 0 20573 M NSW 291A (Example message)
METAR Present Weather Partial Format
ST
X
Mes
sag
e ID
Sen
sor
ID
Sy
stem
sta
tus
Mes
sag
e in
terv
al
Vis
ibil
ity
d
ista
nce
Vis
ibil
ity
un
its
Use
r al
arm
s
Par
ticl
e co
un
t (m
inu
te)
Inte
nsi
ty (
mm
/h)
SY
NO
P C
od
e
ME
TA
R C
od
e
Tem
per
atu
re (
deg
C)
Rel
ativ
e h
um
idit
y*
Ch
eck
sum
(CC
ITT
)
ET
X
Car
riag
e re
turn
Lin
e fe
ed
0x
02
7
M o
r F
0 0
XX
XX
0x
03
0x
0D
0x
0A
7 0 0 12 20673 M 0 0 0 0.00 0 NSW 24.2 -99 BD78 (Example message)
CS120A and CS125 Visibility and Present Weather Sensors
28
METAR Present Weather Full format
ST
X
Mes
sag
e ID
Sen
sor
ID
Sy
stem
sta
tus
Mes
sag
e in
terv
al
Vis
ibil
ity
dis
tan
ce
Vis
ibil
ity
un
its
Av
erag
ing
du
rati
on
Use
r a
larm
s
Sy
stem
ala
rms
12
ch
arac
ters
Par
ticl
e co
un
t (m
inu
te)
Inte
nsi
ty (
mm
/h)
SY
NO
P C
od
e
ME
TA
R C
od
e
Tem
per
atu
re (
deg
C)
Rel
ativ
e h
um
idit
y*
Ch
eck
sum
(C
CIT
T)
ET
X
Car
riag
e R
etu
rn
Lin
e fe
ed
0x
02
8
M o
r F
0 0
0 0
0 0
0…
XX
XX
0x
03
0x
0D
0x
0A
8 0 0 12 20504 M 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.00 0 NSW 24.2 -99 40A2 (Example message)
Relative humidity is only available if a CS215 or HygroVUE probe
temperature and RH sensor is attached. If not this field is “-99”.
11.4 Messages with Generic SYNOP Present Weather Codes (CS125 only)
These messages include simplified, generic present weather codes such as 70 for
snow which may be required for some data collection systems.
Generic SYNOP Present Weather Basic format
ST
X
Mes
sag
e ID
Sen
sor
ID
Sy
stem
sta
tus
Vis
ibil
ity
d
ista
nce
Vis
ibil
ity
u
nit
s
Gen
eric
SY
NO
P c
od
e
SY
NO
P c
od
e
ME
TA
R c
od
e
Ch
eck
sum
(C
CIT
T)
ET
X
Car
riag
e re
turn
Lin
e fe
ed
0x
02
9
M o
r F
XX
XX
0x
03
0x
0D
0x
0A
9 0 0 20481 M 0 0 NSW 73DF (Example message)
*NOTE
Instruction Manual
29
Generic SYNOP Present Weather Partial format S
TX
Mes
sag
e ID
Sen
sor
ID
Sy
stem
sta
tus
Mes
sag
e in
terv
al
Vis
ibil
ity
dis
tan
ce
Vis
ibil
ity
un
its
Use
r a
larm
s
Par
ticl
e co
un
t (m
inu
te)
Inte
nsi
ty (
mm
/h)
Gen
eric
SY
NO
P c
od
e
SY
NO
P c
od
e
ME
TA
R c
od
e
Tem
per
atu
re (
deg
C)
Rel
ativ
e h
um
idit
y (
%)
Ch
eck
sum
(CC
ITT
)
ET
X
Car
riag
e R
etu
rn
Lin
e fe
ed
0x
02
10
M o
r F
0 0
XX
XX
0x
03
0x
0D
0x
0A
10 0 0 12 20909 M 0 0 0 0.00 0 0 NSW 24.2 -99 AB02 (Example message)
Generic SYNOP Present Weather Full format
ST
X
Mes
sag
e ID
Sen
sor
ID
Sy
stem
sta
tus
Mes
sag
e in
terv
al
Vis
ibil
ity
dis
tan
ce
Vis
ibil
ity
un
its
Av
erag
ing
du
rati
on
Use
r a
larm
s
Sy
stem
ala
rms
Par
ticl
e co
un
t (m
inu
te)
Inte
nsi
ty (
mm
/h)
Gen
eric
SY
NO
P c
od
e
SY
NO
P c
od
e
ME
TA
R c
od
e
Tem
per
atu
re (
deg
C)
Rel
ativ
e h
um
idit
y (
%)
Ch
eck
sum
(CC
ITT
)
ET
X
Car
riag
e R
etu
rn
Lin
e fe
ed
0x
02
11
M o
r F
0 0
0 0
0 0
0…
XX
XX
0x
03
0x
0D
0x
0A
11 0 0 12 21342 M 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.00 0 0 NSW 24.3 -99 9AD6 (Example message)
CS120A and CS125 Visibility and Present Weather Sensors
30
Table 11-1. Summary of message IDs and descriptions
Message ID break down
ID Definition
0 Basic format. Contains only distance and system information
1 Partial format. Contains user alarm outputs
2 Full format. Contains all system alarms codes
3* Basic SYNOP present weather format
4* Partial SYNOP present weather format
5* Full SYNOP present weather format
6* Basic METAR present weather format
7* Partial METAR present weather format
8* Full METAR present weather format
9* Generic Basic SYNOP present weather format
10* Generic Partial SYNOP present weather format
11* Generic Full SYNOP present weather format
12 Custom output *CS125 only
Sensor ID break down
ID Definition
0-9 Unit number defined by the user to aid identification of data. Zero by default.
Useful for RS-485 networks. Operates as an address in RS-485 mode
System status break down(1)
Status level Definition
0 No fault
1 Possible degraded performance
2 Degraded performance
3 Maintenance required (1) System status break down reflects the highest level of severity of any active alarm.
Message interval
Time Definition
1-3600 The amount of time, in seconds, between outputs in continuous mode
Visibility distance break down
ID Definition
0-75,000 metres Current visibility distance being detected by the sensor
Visibility units break down
ID Definition
M Metres
F Feet
Averaging duration break down (see note)
ID Definition
1 One minute average
10 Ten minute average
Instruction Manual
31
In accordance with WMO requirements the sensor produces
visibility measurement that are either one or ten minute rolling
averages that are updated at the chosen output interval or when the
sensor is polled. Those averages are not direct averages of MOR
measurements but are averages of extinction coefficient and that
average is then used to calculate the MOR for that period. As the
relationship between extinction coefficient and MOR is not linear it
is possible to see quite rapid changes in MOR that might not be
expected if the result was a rolling average of MOR. Please consider
this, especially when testing the sensor with artificial obscurants or
using the calibration disc.
User alarms
ID Range Definition
1 0-1 Visibility either less or greater than a user specified threshold
2 0-1 Visibility either less or greater than a user specified threshold
Table 11-2. Summary of system alarms and descriptions
System alarms break down
Alarm Range Severity Definition
Emitter failure
(emitter hoods
main LED
output power
level)
0-2 0
3
3
0 = Everything is within normal parameters
1 = Light output level too low
2 = Light output level too high
Emitter lens
dirty(1)
0-3 0
3
1
2
0 = OK. The reported attenuation is below 10%
1 = Reported window signal value is out of range (>30%)
Possible sensor fault or hood could be blocked
2 = Slight dirt build up (10% signal attenuation or higher)
3 = High level of dirt build up (>20%)
Emitter
temperature
0-3 0
1
1
3
0 = Temperature is within operating conditions
1 = Too low. Less than -40°C
2 = Too high. Over 80°C
3 = No sensor detected or below -54°C
Detector lens
dirty(1)
0-3 0
3
1
2
0 = OK. The reported attenuation is below 10%
1 = Reported window signal value is out of range (>30%)
Possible sensor fault or hood could be blocked
2 = Slight dirt build up (10% signal attenuation or higher)
3 = High level of dirt build up (>20%)
Detector
temperature
0-3 0
1
1
2
0 = Temperature is within operating conditions
1 = Too low. Less than -40°C
2 = Too high. Over 80°C
3 = No sensor detected or below -54°C
Detector DC
saturation
level (amount
of background
light seen by
the detector
hood) (1)
0-1 0
2
0 = Within limits
1 = Saturated. The sensor may not be able to perform visibility
readings in some circumstances. Possibly due to high level of
reflections into the detector.
NOTE
CS120A and CS125 Visibility and Present Weather Sensors
32
System alarms break down
Alarm Range Severity Definition
Hood
temperature
0-3 0
1
1
2
0 = Temperature is within operating conditions
1 = Too low. Less than -40°C
2 = Too high. Over 80°C
3 = No sensor detected or below -56°C
External
temperature
(CS125 only)
0-3 0
1
1
2
0 = Temperature is within operating conditions
1 = Too low. Less than -40°C
2 = Too high. Over 80°C
3 = No sensor detected or below -54°C
Signature
error
0-4 0
3
2
2
3
0 = No fault
1 = OS signature error at power up
2 = User memory signature did not match when last read
3 = User memory fault at power up. Secondary copy was
reinstated to correct error.
4 = User memory fault at power up. No secondary copy was
found to reinstate. Factory defaults have been reinstated.
System will need re-calibrating
Flash read
error
0-1 0
3
0 = No errors
1 = One or more errors reading user variables from flash
occurred
Flash write
error
0-1 0
3
0 = No errors
1 = One or more errors writing user variables to flash occurred
Particle limit
(CS125 only)
0-1 0
1
0 = No errors
1 = More particles detected than can be processed
(1)With operating system 14 onwards, to avoid short term appearance of alarms caused by transient events, such as insects or raindrops on the lens, the condition which triggers an increase in alarm level
must persist for 15 minutes before the alarm is set.
Errors are checked every 10 seconds and the next message output is updated with
the following exceptions:
Signature error is checked and reset at power up.
Flash read and write errors are checked when flash memory is updated, for
example when changes are made through the memory structure. They are also
reset on power up.
Particle limit is checked every minute and reset when read.
Particle count*
Range Definition
0-7200 Value represented by an integer number of the current number of particle per minute.
(-99 indicates either an error or that the sensor has been powered less than one minute)
Intensity value*
Range Definition
0 - 999.99 Value represented by a single precision value of the last minutes rainfall intensity in
mm/hr (-99 indicates either an error or that the sensor has been powered up less than
one minute)
SYNOP code*
Range Definition
See Appendix C SYNOP weather code for the last minute as defined by the WMO code table 4680.
(-1 indicates either an error or that the sensor has been powered up less than one
minute)
Instruction Manual
33
Generic SYNOP code*
Range Definition
See Appendix C SYNOP weather code for the last three minutes as defined by the WMO code table
4680 simplified to give generic codes. (-1 indicates either an error or that the sensor
has been powered up for less than one minute)
METAR code*
Range Definition
See Appendix C METAR weather code for the last minute as defined by the WMO code table 4678.
External temperature*
Range Definition
-40.0 - +80.0°C External temperature in degrees Celsius
Relative humidity*
Range Definition
0 - 100 External relative humidity in %RH (-99 indicates either a fault or no CS215 or
HygroVUE T/RH sensor is connected)
*CS125 only, see Appendix C.
11.5 Example sensor message outputs
Full format, visibility only (CS120A default)
2 0 0 10 9622 M 1 0 0 0 0 0 0 0 0 0 0 0 0 46AA
SYNOP present weather full format (CS125 default)
5 0 0 10 112 M 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 6 0.14 52 24.0 -99 9190
METAR present weather full format
8 9 0 60 6682 M 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 54 4.5 63 +RA 20.2 91 ABCD
Where:
9 is the sensor id
60 is the message interval (60 seconds)
6682 is the visibility in metres
M is the visibility units (metres)
54 is particle count
4.5 is intensity (4.5 mm/hr)
63 is the SYNOP code (heavy rain)
+RA is the METAR code (heavy rain)
20.2 is the temperature (20.2 deg. C)
91 is the RH (91%)
ABCD is the checksum
CS120A and CS125 Visibility and Present Weather Sensors
34
11.6 Custom message format
Once a custom message has been formatted it can be output by selecting option 12
from the message - sub 3 menu.
The custom message format allows the CS120A/CS125 message to be modified to
meet particular requirements. The custom message contains a fixed basic set of
variables and up to 16 additional fields.
The custom message output is only available on OS7 and above.
The custom message is as follows:
Custom format
ST
X
Mes
sag
e ID
Un
it I
D
Sy
stem
stat
us
Mes
sag
e
inte
rval
Vis
ibil
ity
dis
tan
ce
Vis
ibil
ity
un
its
Up
to
16
cust
om
fie
lds
C
hec
ksu
m
E
OT
0x02 12 M or F X X X … XXXX 0x04
There are two ways to configure the custom message. The first is through the user
menu system. The second is through the use of logger commands. These logger
commands are MSGSET and MSGGET.
To configure the message using the user menu you will need to enter the sensor
menu system, see the following and Section 15. Entering the sensor menu system.
Return to the message menu 1 and select option 7. You will now be presented
with the list of options shown below:
NOTE
CS125 MESSAGE - SUB 3
Set the message output format. Current format is: FULL SYNOP
- Basic = 0
- Partial = 1
- Full = 2
- Basic SYNOP = 3
- Partial SYNOP = 4
- Full SYNOP = 5
- Basic METAR = 6
- Partial METAR = 7
- Full METAR = 8
- Generic Basic SYNOP = 9
- Generic Partial SYNOP = 10
- Generic Full SYNOP = 11
- Custom output = 12
->
Instruction Manual
35
12 0 0 1 0 92 M1 000000000000 2 0 3 0 92 135 88EF
Menu 1: The message output menu
This will take you to message sub 4 so that the parameters required can be
selected from the available options to configure the message output format;
Enter the number of a custom message field you wish to use and type return. The
screen will update with a 1 next to the chosen field. Repeat for each field you
want then exit the menu. The changes take effect after selecting “Exit and Save”
from the main menu.
Example
In the following example selecting options 1, 3, 4, 10, 15 and 17 puts averaging
duration, system alarms, dirty windows values, SYNOP code, 10 minute average
visibility, and 1 sec visibility into the custom message.
This would give the following output:
Above the custom fields are “1 000000000000 2 0 30 92 135”. The averaging
duration is 1 minute, no system alarms are set, the emitter is reading 2%
contamination, the detector is reading 0% contamination, the SYNOP code is 30,
the 10 minute average visibility is 92 m and the 1 sec reading is 135 m.
CS125 MESSAGE - SUB 4
Configure the message output format:
1 - Averaging duration = 0
2 - User alarms = 0
3 - System alarms = 0
4 - Dirty windows values = 0
5 - Sensor serial number = 0
6 - Particle count = 0
7 - Intensity = 0
8 - Accumulation = 0
9 - Generic SYNOP = 0
10 - SYNOP code = 0
11 - METAR code = 0
12 - NWS code = 0
13 - Temperature (Degrees C) = 0
14 - Humidity (%) = 0
15 - 10 minute ave. vis. = 0
16 - Special 1 = 0
17 - One second vis = 0
18 - Past SYNOP = 0
19 - EXCO = 0
Or, choose 0 to exit when done.
->0
CS125 MESSAGE - MENU 1
ID 0
S/N E1007
(1) Set message format: FULL METAR
(2) Toggle units: METRES
(3) Toggle polled or continuous mode: CONTINUOUS
(4) Set continuous mode message-interval: 1 second(s)
(5) Toggle output averaging period: 1 minute(s)
(6) Sampling interval: 1 second(s)
(7) Configure custom message format
(9) Refresh
(0) Return to main menu
CS120A and CS125 Visibility and Present Weather Sensors
36
The following describes the number of values output.
List of custom output values
Field Description Number of
values output
1 Averaging duration 1
2 User alarms 2
3 System alarms 12
4 Dirty windows values, as percentages, emitter followed by detector 2
5 Sensor serial number 1
6 Particle count (1), particles in the previous minute 1
7 Intensity (1), mm/hr 1
8 Accumulation (1),(2) 1
9 Generic SYNOP (1) 1
10 SYNOP code (1) 1
11 METAR code (1) 1
12 NWS code (1) 1
13 Temperature (degrees C) (1) 1
14 Humidity (%) (1)(3) 1
15 Visibility averaged over the last 10 minutes 1
16 Special 1 (reserved) 1
17 One second visibility(4) 1
18 Past SYNOP 1
19 EXCO 1
(1) These options are only available with a CS125.
(2) This increments to 999.99 mm before resetting to zero. It may be reset to zero at any time with the ACCRES command.
(3) Only outputs a valid value when a CS215/HygroVUE temperature and humidity probe is connected.
(4) The 1 second visibility output is provided ffor special applicationsand research purposes only. This output will have increased noise
levels especially at high visibilities.
12. Interface methods – Device Configuration Utility/Command line/Menu
The sensor can be set up and controlled in one of three ways.
The first method is by using Campbell Scientific’s Device Configuration Utility
Software (DevConfig) which is included with each delivery on the manuals/
resource disk. This software allows an easy menu driven interface for configuring
the sensor on any Microsoft™ based personal computer. All settings can be
accessed using this program.
The program includes online help instructions that describe its general use with
the sensor and also how to load an operating system.
The Device Configurator can also be used as a terminal emulator to use the built-
in menu system of the sensor and to access its calibration menu.
The second method is by using the command line interface where discrete
commands are sent without response from the sensor. This would be the preferred
Instruction Manual
37
method of setting up a sensor if it was connected to a logger for instance. The
configuration setting commands can be sent via a logger to the sensor removing
the need for a local PC to set up the unit.
The third method is by using the simple menu interface built into the sensor
communicating via RS-232 or RS-485, using a terminal emulator program. This
menu system gives access to the more common settings.
All three of these methods use the sensor’s serial connector B to communicate
with the sensor. This can be via the normal communications cable or a
configuration cable as described in Section 8.1.
12.1 Configuring a PC for talking to the sensor
The following describes the procedure for setting up communications using a
terminal emulator program. The terminal emulators built into many Campbell
Scientific software products can also be used.
The following settings should then be used by default:
Bits per second: 38400
Data bits: 8
Parity: none
Stop bits: 1
Flow control: none
Ensure that if the baud rate of the unit has been adjusted and then the
corresponding bits per second value is entered in the port settings of the terminal
emulator. The sensor should now be ready to accept commands.
It is possible to set the sensor into the default communication state via one of the
internal switches on the sensor main board. See Section 9.
13. Definition of the variables that can be set by the user on the sensor
Both DevConfig and the command line interface can access all the user
configurable variables within the sensor. The following lists the acceptable range
and the identification number for these variables along with a short description.
Table 13-1. User definable settings and descriptions
ID Name Range Description Factory
default
1 Sensor ID 0-9 Separate ID used as an extra identifier for a
particular sensor on a network.
0
2 User Alarm 1 Enabled 0-1 User alarm one activation state
0 = Alarm one disabled
1 = Alarm one enabled
0
3 User Alarm 1 Active 0-1 0 = Check if distance is less than ‘User alarm 1
Distance’
1 = Check if distance is greater than ‘User alarm
1 Distance’
0
CS120A and CS125 Visibility and Present Weather Sensors
38
Table 13-1. User definable settings and descriptions
ID Name Range Description Factory
default
4 User Alarm 1 Distance 0-
60000
Distance value that alarm one will trigger against.
This value will correspond to metres or feet
depending upon which is selected in ‘Visibility
Unit’
10000
5 User Alarm 2 Enabled 0-1 User alarm two activation state
0 = Alarm two disabled
1 = Alarm two enabled
0
6 User Alarm 2 Active 0-1 0 = Check if distance is less than ‘User alarm 2
Distance’
1 = Check if distance is greater than ‘User alarm 2
Distance’
0
7 User Alarm 2 Distance 0-
60000
Distance value that alarm one will trigger against.
This value will correspond to metres or feet
depending upon which is selected in ‘Visibility
Unit’
10000
8 Baud rate 0-6 Baud rate for the main RS-232/RS-485 interface
0 = 115200 bps
1 = 57600 bps
2 = 38400 bps
3 = 19200 bps
4 = 9600 bps
5 = 2400 bps
6 = 1200 bps
2
9 Serial number - Internal serial number for the sensor.
(Read only)
-
10 Visibility Unit M or F Unit the visibility value will be presented as
M = metres
F = feet
M
11 Message Interval 1-3600 Interval in seconds between outputs in continuous
mode. This value has no effect if polled mode has
been selected in ‘Measurement mode’
60
12 Measurement mode 0-1 Selects polled or continuous modes.
In continuous mode the sensor will output a string
in the format as set by ‘Message Format’ at
regular intervals as defined by ‘Continuous
Interval’.
0 = Continuous mode
1 = Polled mode
0
13 Message Format 0-12 Output message
0, 1 and 2 = Basic, partial or full visibility
messages
3, 4 and 5 = Basic, partial or full SYNOP
messages
6, 7 and 8 = Basic, partial or full METAR
messages
9, 10 and 11 = Generic basic, partial or full
SYNOP messages
12 = Custom message
5
14 Serial port protocol 0-1 Selects the physical serial interface
0 = RS-232 mode
1 = RS-485 mode
0
15 Averaging period 1 or 10 The period of time that the visibility measurement
is averaged over. Either one minute or ten.
1
Instruction Manual
39
ID Name Range Description Factory
default
16 Sample timing 1-60 Used to define the time interval between sampling
the volume. It is recommended that this value is
left at one except when very low power demands
are needed. Note that 1s sample timing is needed
for present weather measurement. For example:
1 = Sample every second
2 = Sample one second in every two
3 = Sample one second in every three etc.
1
17 Dew heater override 0-1 0 = Allow the sensor to automatically control the
dew heaters
1 = Turn the dew heaters off
0
18 Hood heater override(1) 0-1 0 = Allow the sensor to automatically control the
hood heaters
1 = Turn the hood heaters off
0
19 Dirty window
compensation
0-1 0 = No compensation applied
1 = Compensation for dirt on lenses applied.
The sensor will compensate for up to 10% signal
loss due to dirt per lens.
0
20 Use CRC-16 0-1 0 = Disable command line CRC-16 checking(2)
1 = Enable command line CRC-16 checking
Note: this does not affect communications via
DevConfig or terminal emulator.
0
21 Sensor power down
voltage
7-30 PSU Input voltage level below which the sensor
will enter low power mode. This is usually used to
protect batteries.
7.0
22 Relative humidity(3)
threshold
1-99 Threshold at which the sensor will define
obscuration as liquid or dry if a CS215 is fitted.
80%
(1) Hood heater override needs to be set to ‘1’ (off) when either no hood heaters are installed or
the hood heaters have no power connected to them. This will save power as the relay is not
enabled at low temperatures in this mode.
(2) If disabled the sensor does not check the validity of received data against the checksum sent. It is, however, recommended that checksum checking is enabled to remove any chance of the
sensor being configured incorrectly by accident.
(3) CS125 only.
14. Command line mode The command line interface is broken down into three major commands. These
are GET, SET and POLL. The GET command is used to request all current user
settable values from the sensor. The SET commands sets user settable values and
the POLL command is used to request the current visibility and/or alarm
conditions from the sensor.
The sensor can be configured to expect any commands sent to it to include a valid
checksum. For simple commands, e.g. GET and POLL, fixed value checksums
can be used (see the downloadable example programs at:
www.campbellsci.com/downloads/cs125-example-programs or
www.campbellsci.com/downloads/cs120a-example-programs ).
For more complex SET commands the checksum needs to be calculated (see
Appendix B). The use of the checksum is disabled by defaul